Increased enemy use of supporting arms became a constant concern for the Marines during Prairie III, which starred immediately after Prairie II. At the start of the operation, enemy activity centered on the Cam La and Gio Linh districts. Contact was moderate, generally limited to small enemy groups. Prairie II had blunted earlier NVA intentions in the area, but all indications were that the enemy’s determination to challenge the Marines’ presence had not diminished in spite of heavy casualties.

Anticipating renewed NVA efforts, III MAF held five infantry battalions and four artillery battalions in the area. Battalions at Dong Ha served under the operational control of the 3d Division’s forward headquarters, while those at Camp Carroll and the Rockpile came under the control of the 3d Marines. Additional company-strength outposts were at the Cua Viet port facility, Gio Linh, Mai Loc, Ba Long, and Ca Lu; a two-company outpost was at Khe Sanh. The Marines conducted energetic reconnaissance throughout the area.

The increased operational tempo in the DMZ area placed a heavy strain on Dong Ha logistic facilities. Supplies for the Prairie area of operation arrived at either the Dong Ha airfield, which had been extended to handle C- 130 transports, or they came north from Da Nang by LCUs (landing craft, utility) up the Cua Viet River to Dong Ha. On 18 March, a ma-jot step in easing the logistic burden occurred when an LST (landing ship, tank) ramp opened at Cua Viet. These LSTs could discharge their cargo for tran- shipment up the river by LCUs and LCMs (landing craft, medium). The Cua Viet facility more than tripled the daily tonnage that could be brought in by ships.

A second significant logistic event occurred on the 19th. Route 9 opened from Dong Ha to Khe Sanh, thanks to Lieutenant Colonel Ross L. Mulford’s 11th Engineer Battalion. Mulford’s engineers had worked on the road for months, hindered by terrible weather conditions, mines, and the NVA. The military significance of their effort was considerable, since it reduced the requirement to commit aircraft for logistic support of the Khe Sanh outpost until late summer, when enemy activity closed the road.

When Operation Prairie III started, it appeared that Marine forces continued to face elements of the .324B and the 341st NVA Divisions north of the Ben Hai River. Battalion-size elements of both enemy divisions were in Quang Tn Province, conducting extensive screening and reconnaissance missions, as well as attempting to disrupt the Revolutionary Development Program. Additionally, ARVN units reported that the 808th VC and 814th NVA Battalions were east and south of Quang Tn City.

On 20 March lieutenant Colonel William H. Rice’s Composite Artillery Battalion at Gio Linh came under attack by mortars, rockets, and artillery. The attack demonstrated the enemy’s ability to employ artillery from positions north of the Ben Hai River. Although the bombardment on the 20th was the heaviest, both Gio Linh and Con Thien received almost daily attacks during the next two weeks.

Further evidence of increased enemy activity in the area occurred on 21 March. At 0200 an enemy force ambushed an ammunition re-supply convoy only 300 meters south of Gio Linh. As the convoy approached the artillery position, the enemy struck with heavy small arms and mortar fire, destroying eight trucks and damaging six others. Fortunately, friendly casualties totaled only eight wounded because of the rapid reaction of both the convoy guard and the Gio Linh security company, Company 1, 3d Battalion, 4th Marines.

When Prairie III began, the 3d Battalion, 3d Marines and the 1st Battalion, 9th Marines were conducting a mission in the mountains west of Cam Lo approximately 6,000 meters north of Camp Carroll. The seven-day operation ended on the 21st having made little contact with the enemy, but discovered numerous mortar positions and rocket launching sites, which probably were the positions used in the attack against Camp Carroll on 7 March. A search of the area uncovered 125 large rockets and 3 rocket launchers. Both battalions received orders to sweep north from Cam Lo in support of Operation Beacon Hill being conducted to the east by Seventh Fleet’s SLF.

For some time General Walt had been troubled by growing enemy activity in the region northeast of Dong Ha. His greatest concern was the possibility of an NYA attempt to overrun the Gio Linh artillery base. Its 17 5mm guns were capable of firing at positions deep in North Vietnam. To counter this threat, General Walt asked the commander of U.S. Military Assistance Command Vietnam (ComUSMACV) to have the SLF committed to this area.* CinCPac approved the request on 15 March. Operation Beacon Hill moved into the planning phase, with 19 March set as D-Day.

Bad weather postponed the scheduled landing from ships of the Seventh Fleet’s Amphibious Ready Group until the early afternoon of the 2 0th. Initial operations were unopposed, but BLT 1/4 elements near Gio Linh received fire from enemy supporting arms that night. Company B made contact on the 21st, and the BLT engaged well-entrenched enemy units through the 26th. On 28 March, BLT 1/4 passed to the operational control of the 3d Marines. On 1 April Beacon Hill ended, and III MAF released the BLT to SLF control.

The contribution of Beacon Hill to the Prairie III operation, going on 10 miles to the west, can be measured, in part, by casualty figures. During 12 operational days, BLT 1/4 killed 334 NVA soldiers who otherwise would have been available for use against the battalions involved in Prairie III. Beacon Hill tied up a substantial enemy force. Marine casualties totaled 29 SLF Marines killed and 230 wounded.

To the west of Beacon Hill, other Marines involved in Operation Prairie III experienced similar light contact during the opening phases. The two battalions under command of the 3d Marines — the 3d Battalion, 3d Marines and 1st Battalion, 9th Marines—had moved from the Dong Ha/Dong Ma Mountain complex to Cam Lo on 21 March in preparation for a sweep north to Con Thien. The next morning both battalions jumped off at first light; Lieutenant Colonel Wilder’s 3d Battalion, 3d Marines was on the left and Major Day’s 1st Battalion, 9th Marines was on the right. They encountered light contact during the first two days, but on 24 March Day’s battalion found an NVA battalion southeast of Con Thien. The enemy was in well-prepared defensive positions consisting of mutually supporting bunkers. After two hours of heavy fighting, which included concentrated air and artillery strikes, the enemy withdrew, leaving 33 bodies.

While Major Day’s 1st Battalion attacked the Communist bunker complex, Lieutenant Colonel Wilder’s battalion, on the left, engaged an NVA company. This unit was also well entrenched in camouflaged, reinforced bunkers. The enemy’s light mortars were dug in below ground level, making them even more difficult to locate. Artillery, followed up by an assault by Company I, cracked the position. The NVA broke contact and withdrew, leaving behind 28 bodies, including two uniformed women.

The enemy attempted to delay the Marine advance with harassing mortar and sniper fire for the next two days. By the evening of 26 March the Communist force had broken contact and withdrawn into the DMZ.

On the 28th, the 3d Marines pulled both battalions out of the area and replaced them with Lieutenant Colonel James S. Wilson’s 3d Battalion, 9th Marines. Wilson’s mission was to conduct night ambushes in the area immediately north of Cam Lo. There was very little contact for the first two days, but on the 30th, as Company I completed establishing platoon ambush positions, the NVA attacked the company command post and the 2d platoon’s position. Company I’s positions were approximately six miles northwest of Cam Lo. The Coinmunists walked mortar fire over the position twice, then followed with a ground assault in company strength. The first assault failed when the company commander, Captain Michael P. Getlin, called in supporting arms. As the first attack started, both the 1st and 3d Platoons tried to help the command group and the 2d Platoon, but the enemy stopped the Marines with a cross-fire of automatic weapons. The NYA assaulted a second time. This time they overran the position.

With the help of UH- lE gunships, the company managed to drive off the enemy. The NVA lost 67 killed and 2 captured in both attacks, and a search of the area the following morning turned up a heavy machine gun and 12 automatic weapons. Company It’s losses were heavy. Sixteen Marines died, including the company commander, executive officer, and the weapons platoon commander; 47 more were wounded, including the company first sergeant.

Enemy activity around Quang Tn City increased during the first week of, April. The NVA launched a series of mortar and ground attacks against ARVN positions in the area. On 6 April a Viet Cong unit broke into the Quang Tn provincial jail, freeing more than 200 prisoners.

In spite of this surge of enemy activity to the south, the Marines’ main concerns in the Prairie area continued to be blocking major invasion attempts by the NVA and clearing an anti-infiltration trace between Gio Linh and Con Thien. The second task, included in the development of a strongpoint system, was intended to stop large-scale infiltration in the critical area along the eastern DMZ.*

On 12 April, Major General Bruno A. Hochmuth, lanky Texan who had assumed command of the 3d Marine Division from Major General Kyle the previous month, established a task force around Lieutenant Colonel TheodoreJ. Willis’ 1st Battalion, 4th Marines. ** Its mission was to provide security for Company C, 11th Engineer Battalion. The engineer company was to clear a 200-meter-wide strip from Gio Linh to Con Thien, a distance of 10,600 meters. Willis’ task force was reinforced with a platoon of tanks, an armored amphibian tractor (LVTH-6) platoon, a platoon of M-42 track-mounted dual 40mm guns of the 1st Battalion, 44th Artillery, USA, and some ARVN forces. From the onset the clearing operation proceeded under constant harassment by enemy artillery, mortars, mines, recoilless rifles, and small arms. Despite enemy activity, the Marines had completed approximately half of the strip by 19 April when Operation Prairie III ended.

Prairie III cost the enemy 252 killed, 4 captured, and 128 weapons seized. Marine losses were 56 killed and 530 wounded. The Prairie series was far from over; Prairie IV began the next day in the same place and with the same forces.